Recently, a compact digital camera which has a large-size image sensor to obtain a good blur is proposed. However, when the size of the image sensor is large, it is difficult to reduce the size of the camera since an imaging optical system is also enlarged. Patent Literature 1 (PLT 1) discloses a camera that adds a blur by obtaining information of an object distance while taking an image of substantially a deep focus (an image of an in-focus state for all regions) and performing a predetermined image processing for a shot image. Non-Patent Literature 1 (NPL 1) discloses, with respect to a method of adding the blur, a method of using information of an imaging optical system to use an analytical function such as Gaussian or a thermal diffusion equation. Non-Patent Literature 2 (NPL2) discloses a configuration of performing a high-speed processing for such an image processing with hardware using an accelerator such as GPU.